BEST NED1 NED2 ASTER SRTM1 SRTM3

GPS Visualizer's elevation database coverage

GPS Visualizer hosts DEM (Digital Elevation Model) databases that can add elevation values to GPS data files (click here for more information). The map above shows the geographic extent of the various databases, as of March 2017. The "BEST" link (selected by default) shows which database will be used when "Best available source" is selected.